High frequency attenuator

ABSTRACT

High-frequency thin film chip attenuators can include a substrate having a first side and a second side, a first portion coupled to the first side of the substrate, and a second portion coupled to the second side of the substrate. The first portion can include a ground section, an input contact section, and an output contact section. The second portion can include a ground section, an input section, an output section, and a plurality of resistive sections providing electrical communication between the input section, the output section, and the ground section. The resistive sections can be arranged in an attenuation configuration to attenuate a signal received at the input section and output via the output section. A plurality of through-holes extending through the substrate can provide electrical communication between sections on the first side of the substrate and associated sections on the second side of the substrate.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation application of U.S. application Ser.No. 15/866,015, filed Jan. 9, 2018. The entire content of thisapplication is incorporated herein by reference.

BACKGROUND

Passive chip attenuators are generally used to attenuate signals in acircuit. Various attenuator designs can be used, for example, includingdifferent configurations and/or values of resistors in an attenuatorcircuit design. Such chips often include an attenuator circuit on topside of the chip and a grounding bar on the bottom side of the chip inorder to provide a ground signal to the attenuator circuit. Wrap-aroundcontacts generally travel from the bottom side of the chip to the topside by wrapping around the perimeter edge of the chip, permitting theelectrical communication of ground and signal from the bottom side ofthe chip to the attenuator circuit.

Such designs can lead to poor operating quality for attenuators,particularly when attenuating high frequency signals. For example, toonarrow of a ground strip can lead to impedance matching issues whenattenuating high frequency signals. Impedance mismatch issues at highfrequencies can cause signal reflections or other errors, leading tounpredictable and/or undesirable attenuator operation. In addition, manyattenuators use only a single ground launch from a circuit board intothe attenuator and utilize a single ground trace in a ground-signal(G-S) configuration, which can lead to various signal reflections andlosses.

Additionally, wrap-around contacts tend to contribute to impedancematching issues. When attaching a chip with wrap-around contacts to aboard, it can be difficult to control the geometry of the solder usedfor electrically contacting the wrap-around contacts. This can make itdifficult to maintain a ground-signal-ground (G-S-G) configurationpresent on the circuit board when launching from the circuit board(e.g., that includes a G-S-G configuration) to the attenuator circuit.Losing the desired G-S-G configuration, for example, while launching thesignal to the chip, can lead to various signal reflections and losses,as well as impedance mismatches, particularly at high frequencyoperation. Moreover, wrap-around contacts often create 90° anglesthrough which the signal propagates, further contributing to signalreflections and losses, particularly at high frequencies. Additionally,wrap-around contacts can require fabrication techniques separate fromthose used to construct the rest of the attenuator, such as differentmaterial deposition techniques, and can be difficult to constructuniformly, leading to increased cost and time necessary for attenuatorfabrication.

Single ground-signal (G-S) configurations combined with commonwrap-around contacts can compound the issues that arise in each casewhen attenuating high frequency signals.

Such design characteristics often limit the high-frequency performanceof chip attenuators. Said differently, such characteristics limit thefrequency range that such attenuator chips can operate within thedesired operating parameters (e.g., amount of desired attenuation).Currently, attenuator chips struggle to operate consistently atfrequencies greater than approximately 18 GHz. Thus, as higher frequencysignals become more ubiquitous, improvement in attenuator operation athigher frequencies will be needed.

SUMMARY

Aspects of the disclosure are generally directed toward chipattenuators, and in some examples, thin-film chip attenuators, andmethods of making the same. Some embodiments include a substratecomprising a substrate material having a first side and a second side,the second side being opposite the first. A first portion of theattenuator can be coupled to the first side of the substrate includingan input contact section, an output contact section, and a groundsection, wherein there are no electrically conductive paths between theinput contact section, the output contact section, and the groundsection on the first side of the substrate. In some examples, such afirst portion forms the bottom side of a chip attenuator, and can bemounted to a circuit board. A signal from the circuit board can bereceived via the input contact section, and the ground signal from thecircuit board can be received at the ground section of the firstportion. The ground section on the first side of the substrate can besufficiently large to reduce signal reflections and losses, and tomaintain a desired input impedance at high frequencies.

A second portion of the attenuator can be coupled to the second side ofthe substrate. The second portion can include a first ground sectionpositioned along a first edge of the second side of the substrate and anattenuation section. The attenuation section can include an inputsection, an output section, and a plurality of resistive sectionsproviding electrical communication between the input section, the outputsection, and the first ground section. The resistive sections can bearranged in a plurality of attenuator configurations, such as “tee,”“pi,” and “dual pi” attenuator configurations.

In some examples, a chip attenuator including such first and secondportions can include a plurality of through-holes extending through thesubstrate and providing electrical communication between the first sideof the substrate and the second side of the substrate. In some suchexamples, the input contact section of the first portion is inelectrical communication with the input section of the attenuationsection of the second portion via one or more through-holes. Similarly,in some examples, the output contact section of the first portion is inelectrical communication with the output section of the attenuationsection of the second portion via one or more through-holes.Additionally or alternatively, in some examples, the ground section ofthe first portion is in electrical communication with the first groundsection of the second portion via one or more through-holes.

During operation, a high-frequency signal can be received from a circuitboard at the input contact section of the first portion and communicatedto the input section of the second portion by one or more through-holes.The signal can be attenuated via one or more resistive sections in theattenuation section, and communicated from the output section of thesecond portion to the output contact section of the first portion viaone or more through-holes. The attenuated signal can be communicated tothe circuit board via the output contact section.

The plurality of through-holes can provide electrical communicationbetween the first and second sides of the substrate. In someembodiments, through-holes provide electrical communication between abottom side of a chip attenuator, configured for mounting onto a circuitboard, to a top side of the chip attenuator, including the attenuatingcircuitry. Such through-hole communication can eliminate thehigh-frequency propagation issues and fabrication difficultiesassociated with the traditional wrap-around contacts.

In some examples, various sections of chip attenuators can beconstructed using a plurality of thin-film layers. In some examples,thin-film layers comprise a resistive layer and a conductive layer. Insome examples, the plurality of resistive sections includes only theresistive layer, while other sections include the conductive layer, forexample, in a stack of thin-film materials that also includes theresistive layer.

In some examples, the same thin-film stacks of materials are depositedon the first side and second side of the substrate simultaneously inorder to efficiently construct the attenuator. Various additionalfabrication techniques can be used, for instance, such as masking,etching, and plating, in order to create the various sections of theattenuator, such as the resistive sections, ground sections, and thelike.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a simple diagram of an exemplary chip attenuator.

FIG. 2A shows a simplified plan view showing a first portion of anattenuator coupled to the first side of a substrate.

FIG. 2B shows a simplified plan view showing a second portion of anattenuator coupled to the second side of a substrate.

FIGS. 3A, 3B, and 3C show exemplary plan views of a second portion ofattenuators according to different embodiments.

FIGS. 4A and 4B are cross-sectional views of the “tee” attenuator shownin FIG. 3A taken at lines A-A and B-B, respectively.

FIG. 5 is a process-flow diagram providing an exemplary method forfabricating a thin-film chip attenuator.

FIGS. 6A-6G show plan views of the second section of an attenuatorduring a fabrication process similar to that described with respect toFIG. 5.

FIGS. 7A-7F show plan views of the first section of an attenuator duringa fabrication process similar to that described with respect to FIG. 5.

FIGS. 8A-8D show an alternative process for producing a first portion ofan attenuator.

FIGS. 9A and 9B show first and second portions of an exemplaryattenuator, respectively.

FIG. 10 shows a second portion of an exemplary “tee” attenuator.

FIG. 11 shows a second portion of an exemplary “pi” attenuator.

FIG. 12 shows a second portion of an exemplary “dual pi” attenuator.

DETAILED DESCRIPTION

FIG. 1 shows a simple diagram of an exemplary chip attenuator. Theattenuator 100 includes a substrate 102 having a first side 101 and asecond side 103. The attenuator 100 includes a first portion 110 coupledto the first side 101 of the substrate 102 and a second portion 120coupled to the second side 103 of the substrate 102. In someembodiments, the first portion 110 includes sections configured tocontact a circuit, for example, on a circuit board, for receiving asignal for attenuation and for outputting an attenuated signal. In someembodiments, the second portion 120 of the attenuator 100 includes oneor more resistive sections arranged to provide desired attenuation ofthe signal received via the first portion 110 of the attenuator 100.

FIG. 2A shows a simplified plan view showing a first portion of anattenuator coupled to the first side of a substrate. In the illustratedexample, the first portion 210 includes an input contact section 212, anoutput contact section 214, and a ground section 216. In some examples,the chip attenuator 200 is configured to be surface mounted onto acircuit board via the first portion 210, such as in a land grid array.For example, in some embodiments, the input contact section 212 cancontact part of a circuit board including an input signal to beattenuated and the output contact section 214 can contact part of thecircuit board to receive the attenuated signal. Similarly, the groundsection 216 can contact a ground signal provided by the circuit board.

In an exemplary mounting configuration, a circuit board has aground-signal-ground (G-S-G) configuration, wherein the signal trace isbordered on each side with a ground trace. In some embodiments, to makeelectrical contact to such a configuration, the input contact section212 contacts the signal trace on the circuit board, while the parts ofthe ground section 216 on either side of the input contact section 212contact the ground traces on either side of the signal trace. Thus, theG-S-G configuration of the circuit board continues through the launch ofthe signal (and ground) from the board to the chip attenuator mountedthereon. Maintaining the G-S-G configuration into the attenuator canpromote impedance matching, good high-frequency performance, and reducedreturn losses during attenuator operation (particularly duringattenuation of high-frequency signals, for example, up to or greaterthan 30 GHz). In an exemplary embodiment, the G-S-G configurationprovided by the input contact section 212 and the surrounding parts ofthe ground section 216 in the first portion 210 of the attenuator 200,when contacting a corresponding G-S-G trace on a circuit board, providesa 50Ω input impedance to match the existing circuit parameters.

In the illustrated example of FIG. 2A, the first portion 210 of theattenuator 200 includes isolating sections 213 and 215. In theillustrated example, isolating sections 213, 215 are sections in whichthe substrate 202 does not include additional material disposed thereon.Isolating section 213 provides electrical isolation, at least on thefirst side of the substrate 202, between the input contact section 212and the ground section 216. Similarly, isolating section 215 provideselectrical isolation, at least on the first side of the substrate 202,between the output contact section 214 and the ground section 216. As aresult, in the illustrated embodiment, there are no electricallyconductive paths between the input contact section 212, the outputcontact section 214, and the ground section 216 on the first side of thesubstrate 202.

In some embodiments, isolating section 213 separates the input contactsection 212 from the ground section 216 by a predetermined distance toprevent undesired communication between the input contact section 212and the ground section 216. Similarly, in some examples, isolatingsection 215 separates the output contact section 214 from the groundsection 216 by a predetermined distance to prevent undesiredcommunication between the output contact section 214 and the groundsection 216. In some embodiments, the distance is minimized to maximizethe area of the ground portion 216 while maintaining sufficientisolation between the ground section 216 and the input 212 and output214 contact sections. Maximizing the area of the ground section 216 canhelp maintain a desired input and/or output impedance of the attenuatorand reduce signal reflections and losses during high frequencyoperation.

As shown in the example of FIG. 2A, the attenuator 200 includesthrough-holes 204 a, 204 b, 204 c, 204 d, 204 e, and 204 f. One or moresuch through-holes 204 a-f can extend through the attenuator 200, forexample, to electrically connect parts of the first portion 210 one thefirst side of the substrate to parts of the second portion on the secondside of the substrate. In some embodiments, such as shown in FIG. 2A,through-holes 204 a-f extend through the attenuator 200 at locationsremoved from the periphery of the attenuator. Alternatively, in someexamples, one or more of (and in some embodiments, up to all)through-holes 204 a-204 f are positioned along a peripheral edge of theattenuator 200 such that the perimeter of the attenuator 200 intersectssuch one or more through-holes. In some such examples, one or more suchthrough-holes comprises a semi-circular cross-sectional shape (e.g.,from a plan view perspective).

FIG. 2B shows a simplified plan view showing a second portion of anattenuator coupled to the second side of a substrate. In the illustratedexample, the second portion 220 of the attenuator 200 includes a firstground section 240, a second ground section 242, and an attenuationsection 222 positioned between the first ground section 240 and thesecond ground section 242. In various examples, the attenuation sectioncan include an input section, an output section, and a plurality ofresistive sections. The plurality of resistive sections can provideelectrical communication between the input section, the output section,and at least one of the first ground section 240 and the second groundsection 242 as will be described elsewhere herein. The resistive sectioncan be configured to provide desired attenuation between the inputcontact section 212 and the output contact section 214 of the firstportion 210 of the attenuator 200.

In some examples, as a signal propagates through and is attenuated bythe attenuation section 222, the first ground section 240 and secondground section 242 provide/maintain a G-S-G configuration with respectto the current path through the attenuator 200. This can improveattenuator performance when attenuating high frequency signals (e.g.,signals with frequency up to 30 GHz), for example, by reducing returnloss and impedance matching issues, for example, as described elsewhereherein. In some embodiments, as the signal propagates through theattenuation section 222, the ground section 216 in the first portion 210of the attenuator 200 opposite the attenuation section 222 can maintaina steady and desired input impedance and/or output impedance for theattenuator (e.g., approximately 50Ω).

As further shown in the embodiment of FIG. 2B, through-holes 204 a-fextend through from the first portion 210 of the attenuator 200 to thesecond portion 220 of the attenuator 200. In some embodiments, thethrough-holes 204 a-f can include an electrically conductive coating andprovide electrical communication between various sections of the firstportion 210 and the second portion 220 of the attenuator 200. Forexample, with respect to FIGS. 2A and 2B, through-hole 204 b can provideelectrical communication between the input contact section 212 of thefirst portion 210 and the attenuation section (e.g., an input section)222 of the second portion 220. Similarly, through-hole 204 a can provideelectrical communication between the second ground section 242 of thesecond portion 220 and the ground section 216 of the first portion.

FIGS. 3A, 3B, and 3C show exemplary plan views of a second portion ofattenuators according to different embodiments. FIG. 3A shows a secondportion 320 a of an attenuator having a first ground section 340, asecond ground section 342, and an attenuation section 322 a positionedbetween the first ground section 340 and the second ground section 342.In the example of FIG. 3A, the attenuation section 322 a includes aninput section 324, an output section 326, and a plurality of resistivesections 330 a, 332 a, and 334 a arranged in a “tee” attenuatorconfiguration. In particular, a first resistive section 330 a isprovided between the input section 324 and an intermediate section 328.A second resistive section 332 a is provided between the intermediatesection 328 and the output section 326, and a third resistive section334 a is provided between the intermediate section 328 and the firstground section 340.

In some embodiments, the resistive sections 330 a, 332 a, 334 a comprisea different material and/or stack of materials than do other sections,such as the input section 324, the output section 326, and theintermediate section 328. This distinction in material can lead toresistive properties of the resistive sections 330 a, 332 a, 334 a,while other sections (e.g., input section 324, output section 326,intermediate section 328, first ground section 340, etc.) arecomparatively less resistive.

FIG. 3B shows a second portion 320 b of an attenuator having a firstground section 340, a second ground section 342, and an attenuationsection 322 b positioned between the first ground section 340 and thesecond ground section 342. In the example of FIG. 3B, the attenuationsection 322 b includes an input section 324, an output section 326, anda plurality of resistive sections 330 b, 332 b, and 334 b arranged in a“pi” attenuator configuration. In particular, a first resistive section330 b is provided between the input section 324 and the output section326. A second resistive section 332 b is provided between the inputsection 324 and the first ground section 340, and a third resistivesection 334 b is provided between the output section 326 and the firstground section 340.

Similar to the resistive sections 330 a, 332 a, 334 a described withrespect to FIG. 3A, resistive sections 330 b, 332 b, 334 b can comprisea different material and/or stack of materials than other sections, suchas the input section 324, the output section 326, and the intermediatesection 328. This distinction in material can lead to resistiveproperties of the resistive sections 330 b, 332 b, 334 b, while othersections (e.g., input section 324, output section 326, first groundsection 340, etc.) are comparatively less resistive.

FIG. 3C shows a second portion 320 c of an attenuator having a firstground section 340, a second ground section 342, and an attenuationsection 322 c positioned between the first ground section 340 and thesecond ground section 342. In the example of FIG. 3C, the attenuationsection 322 c includes an input section 324, an output section 326, anda plurality of resistive sections 330 c, 332 c, 334 c, 336 c, and 338 carranged in a “dual pi” attenuator configuration. In particular, a firstresistive section 330 c is provided between the input section 324 andthe second ground section 342. A second resistive section 332 c isprovided between the input section 324 and the first ground section 340.A third resistive section 334 c is provided between the input section324 and the output section 326. A fourth resistive section 336 c isprovided between the output section 326 and the second ground section342. A fifth resistive section 338 c is provided between the outputsection 326 and the first ground section 340.

Similar to the resistive sections 330 a, 332 a, 334 a described withrespect to FIG. 3A, resistive sections 330 c, 332 c, 334 c, 336 c, and338 c can comprise a different material and/or stack of materials thanother sections, such as the input section 324, the output section 326,and the intermediate section 328. This distinction in material can leadto resistive properties of the resistive sections 330 c, 332 c, 334 c,336 c, 338 c while other sections (e.g., input section 324, outputsection 326, first ground section 340, etc.) are comparatively lessresistive.

The exemplary attenuators shown in FIGS. 3A-3C include a plurality ofthrough-holes 304 a, 304 b, 304 c, 304 d, 304 e, 304 f that canfacilitate communication between the illustrated sections in the secondportion (320 a, 320 b, 320 c) of the attenuator to various sections in afirst portion of an attenuator (e.g., first portion 210 in FIG. 2A).Additionally, as described with respect to FIG. 2B, the first groundsection 340 and the second ground section 342 positioned on either sideof attenuation sections (322 a, 322 b, 322 c) can provide a G-S-Gattenuator configuration to facilitate uniform attenuation of highfrequency signals.

In some examples, one of the first ground section 340 and second groundsection 342 can be omitted. For example, in the “tee” and “pi”attenuators shown in FIGS. 3A and 3B, respectively, the second groundsection 342 could be excluded from the second portion 320 of theattenuator 300 while still retaining the desired configuration ofresistive sections (330, 332, etc.). Thus, the attenuation section(e.g., 322 a) can include an input section (e.g., 324 a), an outputsection (e.g., 326 a) and a plurality of resistive sections (e.g., 330a, 332 a, 334 a) providing electrical communication between the inputsection, the output section, and the first ground section (e.g., 340).In some such examples, while the second portion 320 of the attenuator300 does not itself include separate ground sections to form a G-S-Gconfiguration, the G-S-G launch of the signal into the first portion ofthe attenuator (e.g., via input contact section 214 and ground section216 shown in FIG. 2A) may provide the benefits of the G-S-Gconfiguration with respect to overall attenuator operation.

In the illustrated examples of FIGS. 3A-3C, sections of the secondportion 320 a, 320 b, 320 c that do not include the input section 324,the output section 326, the resistive sections (e.g., 330 a, 332 a,etc.), or the intermediate section 328 are shown as only including thesubstrate, shown in a cross-hatched pattern (referred to as substratesections). That is, in various examples, material can be absent from thesurface of the substrate in locations of the attenuator in order tolimit current flow between various sections of the attenuator. Forexample, with respect to FIG. 3A, a bare substrate section is shownbetween the input section 324 and the first ground section 340 in orderto limit the electrical path therebetween to the path through the firstresistive section 330 a, the intermediate section 328, and the thirdresistive section 334 a.

As described, different sections in the attenuator can include differentmaterials and/or layers of materials that can be used to control theresistive properties of the attenuator. In some embodiments, theresistive sections (e.g., 330 a, 332 a, etc.) can include a subset ofthe material present in the remaining sections. FIGS. 4A and 4B arecross-sectional views of the “tee” attenuator shown in FIG. 3A taken atlines A-A and B-B, respectively.

In the illustrated examples in FIGS. 2A, 2B, and 3A-3C, the attenuators200, 300 are arranged to be approximately symmetric in the direction ofsignal propagation through the device. That is, the attenuator can beplaced on a circuit board for attenuating a signal in either direction.However, in various implementations, attenuators need not be symmetric,for example, with respect to layout (e.g., locations of resistivesections 330, 332, etc.) and/or characteristics (e.g., resistance valuesat resistive sections 330, 332, etc.).

FIG. 4A shows an attenuator 300 including a substrate 350 having a firstside 349 and a second side 351. In some examples, the substrate 350comprises a smooth material having a substantially uniform thickness.Such properties can be useful to maintain approximately uniformimpedance and dielectric properties across the substrate and minimizereturn loss. In some examples, the substrate 350 comprises anelectrically insulating material and/or an electrically insulatingcoating.

In some embodiments, substrate 350 comprises an alumina substrate. Insome examples, the substrate comprises 99.6% pure alumina. In otherexamples, substrate can be made from other materials, such as aluminumnitride (AlN), zirconium, silicon (Si), diamond, or the like. In variousexamples, the substrate can be a variety of thicknesses. In someembodiments, the substrate can be less than approximately 650 microns(μm) thick, less than approximately 400 μm thick, less thanapproximately 300 μm thick, or less than approximately 200 μm thick. Insome embodiments, the substrate can be 180 μm thick. Other thicknessesmay also be used.

The attenuator 300 includes a first portion 310 coupled the first side349 of the substrate 350 and a second portion 320 coupled to the secondside 351 of the substrate 350. The first portion 310 includes an inputcontact section 312, an output contact section 314, and a ground section316. In some embodiments, the ground section 316 can include a cut 380separating the ground section 316 into separate sections. Separating theground section 316 into separate sections can be useful, for example,for testing, trimming, and manufacturability purposes, such as providingan ability to electrically isolate various resistive sections (e.g., 332b, 334 b in FIG. 3B) during testing to ensure each section operates asintended. In some examples, surface mounting an attenuator chip to a PCBboard comprises using solder or solder paste to mechanically andelectrically couple the chip to the PCB. Such solder or solder paste canelectrically couple ground sections separated by cut 380 in order toeffectively create a single continuous ground section 316. In somedesigns, a continuous ground section 316 provides electrical coupling ofvarious ground sections (e.g., 340, 342) in the second portion.

In the illustrated example, the first portion includes a plurality oflayers that make up the input contact section 312, the ground section316, and the output contact section 314. In some embodiments, the layersinclude a resistive layer 362, a barrier layer 364, and a conductivelayer 366. In various embodiments, each of the resistive layer 362, thebarrier layer 364, and the conductive layer 366 is a thin-film layer,for example, deposited via one or more thin-film deposition techniques,such as sputtering. In some embodiments, the resistive layer 362, thebarrier layer 364, and the conductive layer 366 together make up a stack367 of thin-film layers. In some embodiments, the stack 367 of thin-filmlayers totals approximately 2000 Angstroms. In some examples, the stackof thin-film layers totals less than 2000 Angstroms.

In an exemplary embodiment, the resistive layer 362 comprises aresistive material, such as nickel chromium (NiCr), tantalum nitride(TaN) or the like. Similarly, the conductive layer 366 could include anyof a plurality of conductive materials, such gold, silver, copper, orthe like. In some embodiments, the barrier layer 364 preventscontamination of the resistive layer 362 from the conductive layer 366,and can be selected based on the materials used in the resistive layer362 and the conductive layer 366. For instance, in an exemplaryembodiment, the resistive layer 362 comprises nickel chromium and theconductive layer 366 comprises copper, which can leach into and degradenickel chromium over time. In some such examples, barrier layer 364comprises nickel, and acts to prevent copper from contaminating thenickel chromium resistive layer 362. Thus, the barrier layer 364 canprevent degradation of the resistive layer 362 over time. In someembodiments, barrier layer 364 can be omitted, for example, if theresistive layer 362 and conductive layer 366 materials are compatibleand/or to save manufacturing time and cost.

The first portion 310 further includes a plated layer 368 on the stack367 of thin-film materials. The plated layer 368 can include a copperplated layer. In some embodiments, the plated layer 368 is significantlythicker than any of the thin-film resistive layer 362, barrier layer364, and conductive layer 366, and can reduce losses due to a skineffect of thin-film layers (e.g., stack 367).

In the illustrated embodiment, the first portion 310 includes isolatingsections 313 and 315 separating the ground section 316 from the inputcontact section 312 and the output contact section 314, respectively. Asshown, none of the layers 362, 364, 46, 368 is continuous across theisolating sections 313, 315. Accordingly, there are no electricallyconductive paths between the input contact section 312, the outputcontact section 314, and the ground section 316 on the first side 349 ofthe substrate 350. As can be seen, in the illustrated example thesubstrate 350 would be visible in isolating sections 313 and 315 in a ina plan view of the first portion 310 of the attenuator 300.

Similar to as shown in FIG. 3A, the second portion 320 coupled to thesecond side 351 of the substrate includes an input section 324, anintermediate section 328, and an output section 326. The second portion320 further includes a first resistive section 330 a coupling the inputsection 324 and the intermediate section 328, and a second resistivesection 332 a coupling the intermediate section 328 and the outputsection 326 (such as shown in the “tee” configuration of FIG. 3A).

In the example of FIG. 4A, the input section 324, the output section326, and the intermediate section 328 include a plurality of layers. Insome embodiments, the layers include a resistive layer 372, a barrierlayer 374, and a conductive layer 376. In various embodiments, each ofthe resistive layer 372, the barrier layer 374, and the conductive layer376 is a thin-film layer, for example, deposited via one or morethin-film deposition techniques, such as sputtering. In someembodiments, the resistive layer 372, the barrier layer 374, and theconductive layer 376 together make up a stack 377 of thin-film layers.

Similar to the first portion 310 of attenuator 300, in an exemplaryembodiment, the resistive layer 372 comprises a resistive material, suchas nickel chromium (NiCr), tantalum nitride (TaN) or the like. In someembodiments, the barrier layer 374 comprises a nickel (Ni) layer. Instill further embodiments, the conductive layer 376 comprises a copper(Cu) layer. In some such embodiments, the barrier layer 374 preventscontamination of the resistive layer 372 from the conductive layer 376.The second portion 320 further includes a plated layer 378 on the stack377 of thin-film materials. The plated layer 378 can include a copperplated layer. In some embodiments, the plated layer 378 is significantlythicker than any of the thin-film resistive layer 372, barrier layer374, and conductive layer 376 and can reduce loss due to a skin effectof thin-film layers (e.g., stack 377).

In the illustrated embodiment of FIG. 4A, each of the input section 324,the intermediate section 328, and the output section 326 each includesthe thin-film stack 377 of the resistive layer 372, the barrier layer374, and the conductive layer 376, as well as plated layer 378. However,the first resistive section 330 a and the second resistive section 332 ainclude only the resistive layer 372 on the second side 351 of substrate350. Thus, a signal propagating from the input section 324 to the outputsection 326 travels through a thin-film resistive layer 372 in resistivesections 330 a and 332 a. The backing ground section 316 opposite thepropagating signal can provide a steady input impedance and/or outputimpedance (e.g., at approximately 50Ω) for the attenuator, even duringhigh frequency attenuation.

In the illustrated example, through-holes 304 b and 304 e extend throughthe substrate 350 between the first portion 310 and the second portion320. In some examples, through-hole 304 b comprises an electricallyconductive coating (e.g., thin-film stack 367 or 377) and provideselectrical communication between input contact section 312 of the firstportion 310 and the input section 324 of the second portion 320.Similarly, in some embodiments, through-hole 304 e comprises anelectrically conductive coating (e.g., thin-film stack 367 or 377) andprovides electrical communication between output contact section 314 ofthe first portion 310 and the output section 326 of the second portion320. In general, through-holes (e.g., 304 b, 304 e) can provideelectrical communication between the first portion 310 on the first side349 of the substrate 350 and the second portion 320 on the second side351 of the substrate 350.

In the illustrated example, through-holes 304 b and 304 e include anhourglass shape and rounded edges at the surfaces of plating layers 368,378. In some examples, one or both of the hourglass shape and roundededges are a byproduct of the fabrication process of the through-holes.For example, in an exemplary embodiment, through-holes 304 b, 304 e area result of through-holes formed in the substrate 350. In some examples,the through-holes formed in the substrate are approximately hourglassshaped, similar to through-holes 304 b, 304 e in FIG. 4A, for example,due to the process by which the through-holes are formed in thesubstrate. In some examples, the through-holes are formed in thesubstrate due to a laser pulse incident on the substrate 350. The laserpulse can create an hourglass shaped through-hole in the substrate 350including rounded corners at the first side 349 and second side 351 ofsubstrate 350. Adding layers (resistive layer 362, barrier layer 364,conductive layer 366, plating layer 368, etc.) can result in such layershaving a similar hourglass shape and rounded edges at the layer surface.In some such examples, electrical communication between the firstportion 310 and the second portion 320 may be provided by conductivepaths via through-holes 304 b, 304 e that do not include right anglesthrough which the current flows, reducing loss during high frequencytransmission.

In the cross-sectional view of FIG. 4B, attenuator 300 includes a firstportion 310 coupled the first side 349 of the substrate 350 and a secondportion 320 coupled to the second side 351 of the substrate 350. At thecross-sectional plane shown in FIG. 4B, the first portion 310 includesground section 316 as in FIG. 4A, including resistive layer 362, barrierlayer 364, conductive layer 366, and plated layer 368. In the planeshown in FIG. 4B, first portion 310 includes isolating sections 313 and315, however, input contact section 312 and output contact section 314are not present at the cross-sectional plane at line B-B in FIG. 3A.

In the view of FIG. 4B, the attenuator 300 further includes secondportion 320 coupled to the second side 351 of the substrate 350. At theplane shown in FIG. 4B, the second portion 320 includes a thirdresistive section 334 including only resistive layer 372.

With reference back to FIG. 3A, in some examples, the resistive sections330 a, 332 a, 334 a can include only a resistive layer (e.g., layer 372as shown in FIGS. 4A and 4B), and therefore have a sheet resistancedependent on the dimensions of the resistive sections. Accordingly, thesheet resistance of each resistive section 330 a, 332 a, 334 a can becustomized by adjusting the dimensions of such resistive sections inorder to match the desired attenuation characteristics of attenuator.

Exemplary operation of a “tee” attenuator such as shown in FIGS. 3A, 4A,and 4B will be described with reference to these figures. A chipattenuator 300 can be surface mounted, for example, onto a circuitboard, such that input contact section 312 contacts the part of thecircuit board that includes the signal to be attenuated and outputcontact section 314 contacts the part of the circuit board that receivesthe attenuated signal. Ground section(s) 316 contact a part of thecircuit board that is grounded.

The signal to be attenuated is received at the input contact section312, and is directed to the input section 324 of the second portion 320via the through-hole 304 b. The signal does not short from the inputcontact section 312 to ground section 316 in the first portion 310 ofthe attenuator 300 since the input contact section 312 and the groundsection 316 are separated by isolating section 313.

The signal at input section 324 propagates through attenuation section322 a to output section 326, and is attenuated by the “tee”configuration of resistive sections 330 a, 332 a, and 334 a due to thesheet resistance of resistive layer 372 at such sections. The attenuatedsignal is received from the output section 326 by the output contactsection 314 via through-hole 304 e, and can be communicated to othercomponents on the circuit board via the output contact section 314. Theground section 316 on the first portion 310 generally opposite of theattenuation section 322 a, as well as the G-S-G configuration in thesecond portion 320 (including first ground section 340, attenuationsection 322 a, and second ground section 342) can reduce return lossesand maintain a desired input and/or output impedance (e.g.,approximately 50Ω).

According to such an exemplary embodiment, the through-holes (e.g., 304b, 304 e) allow the attenuator 300 to receive signals at the bottom ofthe attenuator while allowing for a large ground plane (e.g., groundsection 316) on the bottom of the attenuator while transmitting dataacross the top of the attenuator. Further, such through-holes eliminatethe need to transmit data from one side of the attenuator to the othervia any wrap-around contacts, which can create operating performanceissues, especially at high frequencies, as described elsewhere herein.For example, communication via through-holes can eliminate undesirableand/or unpredictable effects of solder fillets (e.g., impedancemismatch) and right angle current paths associated with wrap-aroundcontacts. Incorporating through-holes rather than wrap-around contactscan further improve fabrication speed and efficiency, for example,eliminating the requirement for separate and/or complex depositionand/or plating techniques required for wrap-around contacts.

In some examples, the stack 377 of thin-film layers coupled to thesecond side 351 of the substrate 350 is approximately the same (e.g.,same composition, thickness, etc.) as the stack 367 of thin-filmmaterials coupled to the first side 349 of the substrate 350. Forinstance, in an exemplary embodiment, each of resistive layers 362 and372 comprises a NiCr film, each of barrier layers 364 and 374 comprisesa Ni film, each of conductive layers 366 and 376 comprises a Cu film,and each of plated layers 368 and 378 comprises a Cu-plated layer. Insome examples, thin-film stacks 367 and 377 can be formedsimultaneously, for example, during a thin-film deposition process. Thiscan reduce the time and materials needed to produce a chip attenuator,as various materials can be deposited on both sides of the attenuatorsimultaneously.

Alternatively, in some embodiments, various layers can be deposited onthe first side and second side of the substrate separately. In some suchembodiments, with respect to the fabrication shown in FIGS. 4A and 4B,the first portion 310 of the attenuator 300 can exclude the resistivelayer 362 and the barrier layer 364, since there are no resistivesections in the first portion of the substrate to make use of theresistive material. Further, with no resistive layer 362, a barrierlayer 364 used to protect the resistive layer 362 from the conductivelayer 366 may similarly be omitted.

FIG. 5 is a process-flow diagram providing an exemplary method forfabricating a thin-film chip attenuator. The method of FIG. 5 includesforming a plurality of through-holes in a substrate material (500) anddepositing a thin-film stack of materials on the substrate (510). Insome examples, depositing the thin-film stack comprises depositing aNiCr resistive layer, a Ni barrier layer, and a Cu conductive layer onboth sides of the substrate, for example, via a sputtering process. Insome embodiments, the sputtering process can be performed on both thefirst side and the second side of a substrate simultaneously. In someexamples, depositing the thin-film stack results in depositing aconductive coating on an interior surface of one or more of thethrough-holes formed in step 500 to enable conduction of electricalsignals through the formed through-holes.

The method further includes the step of masking the thin-film stack, andetching the unmasked sections to remove the stack from various sectionsof the attenuator (e.g., cross-hatched sections shown in FIG. 3A,isolating sections 213, 215 in FIG. 2A). The method then includesmasking the substrate sections and resistive sections (530), forexample, the resistive sections 330 a, 332 a, 334 a in FIG. 3A andcross-hatched substrate section and copper plating the unmasked sections(540). For example, with respect to FIG. 3A, the first ground section340, the second ground section 342, the input section 324, the outputsection 326, and the intermediate section 328 would be copper plated atstep 540, while the remaining sections would be masked from the copperplating.

Next, the mask can be removed, and the attenuator can etched to anetchant that removes the conductive layer and the barrier layer, but notthe resistive layer, from the resistive sections (550). For instance,with respect to FIG. 4A, the barrier layer 374 and the conductive layer376 can be etched away from resistive sections 330 a and 332 a, whilethe resistive layer 372 remains, thereby creating sheet resistorsbetween the input section 324, intermediate section 328, and outputsection 326. The masking such sections in step 530 would prevent theplated layer 378 from being plated on such sections in step 540, and asufficiently thick plated layer 378 at the input section 324, theintermediate section 328, and the output section 326 would prevent theetching at step 550 from damaging the conductive layer 376 or thebarrier layer 374 in such sections.

In some examples, the step of etching the thin-film stack to thesubstrate (520) is performed on both the first portion and the secondportion of the attenuator, for example, to form substrate section on thesecond portion and to create isolating sections (e.g., 313, 315) in thefirst portion. In other examples, such etching is performed on only thesecond portion, and the stack remains continuous on the first portion.In some such examples, the method includes the step of protecting thesecond portion of the attenuator and etching the thin-film stack fromthe isolating sections (e.g., 313, 315) in the first portion (560).

In some examples, the method includes the step of trimming the formedresistive sections (570). This can include, for example, laser trimmingthe resistive sections so that the resistance of such sections meets adesired resistance. For example, in some cases, laser trimming is moreprecise than masking and etching. Thus, resistive sections can be madewider than desired during the masking and etching processes, and thentrimmed to the desired dimensions to result in the desired dimensions,and therefore resistance.

FIGS. 6A-6G show plan views of the second section of an attenuatorduring a fabrication process similar to that described with respect toFIG. 5. FIG. 6A shows a substrate material 650 (shown in a cross-hatchedpattern) with through-holes 604 a-604 f formed therein (e.g., via step500). Forming the through-holes can be performed a variety of ways,including via a mechanical punch, applying one or more laser pulses, orthe like. FIG. 6B shows the substrate including a thin-film stack 677deposited thereon (e.g., step 510).

FIG. 6C shows a shaded mask 690 applied to various sections of thethin-film stack 677. After etching the thin-film stack and removing themask, FIG. 6D shows the thin-film stack 677 remaining where the shadedmask 690 was applied in FIG. 6C, while sections of the stack 677 fromFIG. 6C have been etched down to the substrate 650 (crosshatched) inFIG. 6D, such as described in step 520 in the method of FIG. 5.

FIG. 6E shows a shaded mask 692 applied to various sections of thesecond portion of the attenuator, leaving remaining exposed sections ofthe thin-film stack 677, such as described in step 530 of FIG. 5. FIG.6F shows that a plating layer 678 has been applied to unmasked sections(of stack 677) in FIG. 6E, while the thin-film stack 677 and substrate650 material remains where mask 692 was applied, such as described withrespect to step 540 in FIG. 5. Finally, the sections showing thethin-film stack 677 in FIG. 6F are etched to remove the conductive layerand the barrier layer in order to reveal the resistive layer at sections672, as shown in FIG. 6G and as described in step 550. Such sectionscould be trimmed to a desired size as described with respect to step570. The resulting structure after the process shown in stepsrepresented in FIGS. 6A-6G is similar to the “tee” attenuator shown inFIG. 3A, including a plurality of resistive sections and first andsecond ground sections.

Similarly, FIGS. 7A-7F show plan views of the first section of anattenuator during a fabrication process similar to that described withrespect to FIG. 5. The process shown in FIGS. 7A-7F can be performedsimultaneously with the process shown in FIGS. 6A-6G, for example, bysputtering onto and etching both sides of an attenuator structuresimultaneously.

FIG. 7A shows a substrate material 650 (shown in a cross-hatchedpattern) with through-holes 604 a-604 f formed therein (e.g., via step500 and as shown in FIG. 6A). FIG. 7B shows the substrate including athin-film stack 677 deposited thereon (e.g., step 510 and as shown inFIG. 6B).

FIG. 7C shows a shaded mask 690 applied to various sections of thethin-film stack 677. After etching the thin-film stack and removing themask, FIG. 7D shows the thin-film stack 677 remaining where the shadedmask 690 was applied in FIG. 7C, while sections of the stack 677 fromFIG. 7C have been etched down to the substrate 650 (crosshatched) inFIG. 7D, such as described in step 520 in the method of FIG. 5 and shownin FIG. 6D.

FIG. 7E shows a shaded mask 692 applied to various sections of the firstportion of the attenuator, leaving remaining exposed sections of thethin-film stack 677, such as described in step 530 of FIG. 5 and shownin FIG. 6E on the second portion of the attenuator. FIG. 7F showsapplying a plating layer 678 to unmasked sections (of stack 677) in FIG.7E, while the substrate 650 material remains where mask 692 was applied,such as described with respect to step 540 in FIG. 5. The resultingstructure after the process shown in steps represented in FIGS. 7A-7F issimilar to the first portion of the attenuator shown in FIG. 2A,including input and output sections separated from a ground section byisolating sections including a bare substrate.

Thus, the process described in FIG. 5 can be applied to two sides of asubstrate simultaneously to produce the first and second portions of anattenuator during a single processing step. For instance, the processsteps performed for creating the second portion of the attenuatorhighlighted in FIGS. 6A, 6B, 6C, 6D, 6E, and 6F can be performedsimultaneously as the process steps performed for creating the firstportion of the attenuator highlighted in FIGS. 7A, 7B, 7C, 7D, 7E, and7F, respectively.

FIGS. 8A-8D show an alternative process for producing a first portion ofan attenuator. FIG. 8A shows a first side of a substrate including athin-film stack 677 including a plurality of through-holes, similar todescribed with respect to steps 500 and 510. FIG. 8B shows a mask 692applied to sections to not be copper plated, similar to the maskdescribed in step 530 of FIG. 5 and shown in FIG. 6E. In FIG. 8C, theunmasked sections are plated with plating layer 678, while thin-filmstack 677 remains where mask 692 was placed. The entire thin-film stack677 can be etched away to reveal substrate 650 as described with respectto step 560 in FIG. 5, for example, while protecting resistive sectionson the second portion of the attenuator.

FIGS. 9A and 9B show first and second portions of an exemplaryattenuator, respectively. Similar to embodiments described elsewhereherein, the attenuator of FIG. 9A shows a first portion 910 of anattenuator 900 that includes an input contact section 912, an outputcontact section 914, and a ground section 916. In some examples, groundsection 916 includes one or more separate sections 916 a, 916 bseparated by a cut or gap 917 in the ground section 916. Such a cut orgap 917 can be formed during an etching process such as during step 520or 560 in FIG. 5. Ground section 916 is separated from input contactsection 912 via isolating section 913, and from output contact section914 via isolating section 915. In some embodiments, input contactsection 912, output contact section 914, and ground section 916 includea plating layer, applied, for example, as described in step 540 in FIG.5.

FIG. 9B shows a second portion 920 of an attenuator 900 that includes afirst ground section 940 and a second ground section 942. The secondportion 920 includes an input section 924, an output section 926, and anintermediate section 928. In some examples, input section 924, outputsection 926, and intermediate section 928 include a plating layerapplied, for example, as described in step 540 in FIG. 5 and shown inFIG. 6F.

The attenuator 900 in FIGS. 9A and 9B comprises a “tee” attenuator. Thesecond portion 920 includes a first resistive section extending betweenthe input section 924 and the intermediate section 928, a secondresistive section extending between the intermediate section 928 and theoutput section 926, and a third resistive section extending between theintermediate section 928 and the first ground section 940. Resistivesections 930, 932, 934 can include a resistive layer and can be formed,for example, by etching down a stack of materials to reveal theresistive layer, such as described with respect to step 550 in FIG. 5and as shown in FIG. 6G.

The attenuator comprises a plurality of through-holes 904 a, 904 b, 904c, 904 d, 904 e, 904 f extending between the first portion 910 and thesecond portion 920. As described elsewhere herein, through-holes 904a-904 f can include an electrically conductive coating to facilitateelectrical communication between the first portion 910 and the secondportion 920. For example, in the illustrated example of FIGS. 9A and 9B,through-holes 904 a and 904 d provide electrical communication betweenthe ground section 916 of the first portion 910 and the second groundsection 942 in the second portion 920. Similarly, through-holes 904 cand 904 f provide electrical communication between the ground section916 of the first portion 910 and the first ground section 940 in thesecond portion 920. Thus, first ground section 940 and second groundsection 942 in FIG. 9B are electrically coupled via through-holes 904 a,904 c, 904 d, 904 f, and the ground section 916. This provides a G-S-Gconfiguration on the second portion 920 of the attenuator 900.

Additionally, through-hole 904 b provides electrical communicationbetween input contact section 912 of the first portion 910 and inputsection 924 of the second portion 920. Similarly, through-hole 904 eprovides electrical communication between output contact section 914 ofthe first portion 910 and output section 926 of the second portion 920.

During operation, attenuator 900 can be surface mounted onto a circuitboard with the first portion 910 facing down onto the board, such as ina land grid array. A signal to be attenuated via attenuator 900 can bereceived at the input contact section 904 and communicated to the inputsection 924 via through-hole 904 b. The signal can be attenuated viatransmission across the “tee” attenuator configuration includingintermediate section 928 and resistive sections 930, 932, 934. Asdescribed, first ground section 940 and second ground section 942 oneither side of intermediate section 928 and resistive sections 930, 932,934 provide a G-S-G configuration to facilitate high frequency signalattenuation with reduced loss. The attenuated signal can be received atoutput section 926 and communicated to output contact section 914 viathrough-hole 904 e. Output contact section 914 can transmit theattenuated signal back to the circuit board, for instance, via a directcontact to the surface of the board.

Fabrication and operation of a “tee” structure have been described andshown with respect to FIGS. 6A-D and 9. However, it will be appreciatedthat similar fabrication processes will be applicable for otherattenuators, such as “pi” attenuators (e.g., as shown in FIG. 3B), “dualpi” attenuators (e.g., as shown in FIG. 3C), and the like. Theground-signal-ground (G-S-G) configuration of the attenuators, as wellas the backing ground section on the first portion of the attenuatorsand the plating layer, reduce various losses often experienced withthin-film attenuators when attenuating high frequency signals. Processesdescribed herein can be used to fabricate such high-frequency thin-filmattenuators, for example, on a surface mount chip.

In various examples, the specific plan arrangement of various sections,such as the size and positions of various resistive sections, can beadjusted in order to customize the attenuation properties of theattenuator. For example, the geometry of thin film resistive sectionscan be adjusted to achieve a desired sheet resistance across a givenresistive section. In various examples, the shape, size, and/or locationof various sections (e.g., input section 924, intermediate section 928,output section 926, etc.) can be adjusted to facilitate the desiredgeometric configuration of resistive sections extending therebetween.

In some embodiments, different attenuator configurations (e.g., “tee,”“pi,” etc.) can best facilitate a desired level of attenuation, forexample, due to physical limitations for achieving appropriateresistance values within a single thin-film attenuator chip. Forinstance, in some implementations, 1 dB and 2 dB attenuators areconfigured using a “tee” attenuator design, 3 dB, 4 dB, 5 dB, 6 dB, and7 dB attenuators are configured using a “pi” attenuator design, and 8dB, 9 dB, and 10 dB attenuators are configured using a “dual pi”attenuator design.

It will be appreciated that various thin-film deposition techniquescould be used to fabricate thin-film attenuators as described herein,such as by vapor deposition, vacuum deposition, evaporation, screenprinting, electroplating, immersion plating/coating, organic materialgrowth, foil processing, or other known processes. In general, variousprocesses that can be used to deposit thin-film layers of a desiredthickness may be used in fabricating thin-film attenuators.

Additionally, while often described as being fabricated using thin-filmdeposition techniques followed by various masking and etching steps(e.g., destructive fabrication), in some embodiments, one or moreattenuator designs described herein could be fabricated using additivefabrication techniques. For instance, combinations of masking anddepositing steps, 3D printing techniques, thick-film fabricationtechniques, or the like could be used to make larger scale versions ofsuch attenuator chips. In general, one or more thick-film, thin-film,metallization, or other resistive element and conductive elementconstructive processes can be used to build various devices as describedherein.

Various exemplary features and fabrication techniques have beendescribed. FIGS. 10-12 show a series of second portions of exemplaryattenuator configurations. FIG. 10 shows a second portion of anexemplary “tee” attenuator. In the illustrated example, attenuatorincludes an input section 1024 having a first through-hole 1004 a forreceiving an input signal to be attenuated, for example, from an inputconnection section on a bottom side of the attenuator. The attenuatorfurther includes an output section 1026 having a third through-hole 1004c for communicating an attenuated signal, for example, to an outputconnection section on a bottom side of the attenuator. The attenuatorincludes a ground section 1040. In some embodiments, the attenuatorcould further include a second ground section (not shown) positionedgenerally opposite ground section 1040. Ground section 1040 includes asecond through-hole 1004 b and a fourth through-hole 1004 d forgrounding the ground section 1040 to a ground section on the bottom sideof the attenuator.

The attenuator of FIG. 10 includes an intermediate section 1028, a firstresistive section 1030 between the input section 1024 and theintermediate section 1028, a second resistive section 1032 between theintermediate section 1028 and the output section 1026, and a thirdresistive section 1034 between the intermediate section 1028 and theground section 1040. The first 1030, second 1032, and third 1034resistive sections, together with the intermediate section 1038, form a“tee” attenuator between the input section 1024 and the output section1026, and similarly between first through-hole 1004 a and thirdthrough-hole 1004 c.

In the illustrated example, the input section 1024 has an extension 1090extending from the first through-hole 1004 a and effectively moving thesignal flow path further away from the ground section 1040 and extendingthe length of third resistive section 1034 required to extend from theintermediate section 1028 to the ground section 1040. Similarly, groundsection 1040 includes cutaway section 1041 proximate the location thatthe third resistive section 1034 meets ground section 1040. Extension1090 and cutaway section 1041 effectively increase the length of thirdresistive section 1034. Reducing the amount that cutaway section 1041cuts into the ground section 1040 and/or reducing the length of theextension 1090 would effectively shorted the length of third resistivesection 1034. Varying the length of third resistive section 1034 changesthe resistance of the resistive section, and can be adjusted accordingto desired attenuation properties. Similarly, the widths and/or lengthsof first resistive section 1030 and/or second resistive section 1032 canbe adjusted to adjust the resistance of such sections, and similarly,the attenuation properties of the attenuator.

FIG. 10 includes a schematic trace of a circuit diagram showing the“tee” attenuator configuration. As shown, the schematic circuit includesresistors R₁ (corresponding to first resistive section 1030), R₂(corresponding to second resistive section 1032), and R₃ (correspondingto third resistive section 1034). It will be appreciated that, in such a“tee” configuration attenuator, adjusting the values of resistors R₁,R₂, or R₃ will adjust the attenuation characteristics of the attenuator.Thus, adjusting the geometry of resistive sections 1030, 1032, and/or1034 can similarly impact the attenuation characteristics of theattenuator.

FIG. 11 shows a second portion of an exemplary “pi” attenuator. In theillustrated example, attenuator includes an input section 1124 having afirst through-hole 1104 a for receiving an input signal to beattenuated, for example, from an input connection section on a bottomside of the attenuator. The attenuator further includes an outputsection 1126 having a third through-hole 1104 c for communicating anattenuated signal, for example, to an output connection section on abottom side of the attenuator. The attenuator includes first groundsection 1140 a and second ground section 1140 b. In some embodiments,the attenuator could further include one or more additional groundsections (not shown) positioned generally opposite ground sections 1140a and 1140 b. First ground section 1140 a includes second through-hole1104 b, and second ground section 1140 b includes a fourth through-hole1104 d for grounding the first and second ground sections 1140 a and1140 b to a ground section on the bottom side of the attenuator. In someexamples, the ground section on the bottom side of the attenuator (e.g.,in a first portion of the attenuator) electrically couples first andsecond ground sections 1140 a and 1140 b via second through-hole 1104 band fourth through-hole 1104 d.

The attenuator of FIG. 11 includes a first resistive section 1130between the input section 1124 and the output section 1126, a secondresistive section 1132 between the input section 1124 and the firstground section 1140 a, and a third resistive section 1134 between theoutput section 1126 and the second ground section 1140 b. The first1130, second 1132, and third 1134 resistive sections form a “pi”attenuator between the input section 1124 and the output section 1126,and similarly between first through-hole 1104 a and third through-hole1104 c.

FIG. 11 includes a schematic trace of a circuit diagram showing the “pi”attenuator configuration. As shown, the schematic circuit includesresistors R₄ (corresponding to first resistive section 1130), R₅(corresponding to second resistive section 1132), and R₆ (correspondingto third resistive section 1134). It will be appreciated that, in such a“pi” configuration attenuator, adjusting the values of resistors R₄, R₅,or R₆ will adjust the attenuation characteristics of the attenuator.Thus, adjusting the geometry of resistive sections 1130, 1132, and/or1134 can similarly impact the attenuation characteristics of theattenuator. For example, similar to as discussed with respect to theexemplary “tee” attenuator in FIG. 10, adjustments to variousdimensional characteristics of one or more sections, such as the inputsection 1124, output section 1126, first ground section 1140 a, orsecond ground section 1140 b can customize the resistance of theresistive sections 1130, 1132, 1134 of the attenuator, and thus theattenuating characteristics of the attenuator. For example, extension1190 on the input section 1124 and cutaway section 1141 act to increasethe length of the second resistive section 1132 between the inputsection 1124 and the first ground section 1140 a compared to if suchsections extended straight across along the attenuator. In theillustrated example, similar geometry is included on the output section1126 and second ground section 1140 b.

FIG. 12 shows a second portion of an exemplary “dual pi” attenuator. Inthe illustrated example, attenuator includes an input section 1224having a second through-hole 1204 b for receiving an input signal to beattenuated, for example, from an input connection section on a bottomside of the attenuator. The attenuator further includes an outputsection 1226 having a fifth through-hole 1204 e for communicating anattenuated signal, for example, to an output connection section on abottom side of the attenuator.

The attenuator includes first ground section 1240 a, a second groundsection 1240 b, a third ground section 1240 c, and a fourth groundsection 1240 d. In the illustrated embodiment, first ground section 1240a includes a third through-hole 1204 c, second ground section 1240 bincludes a sixth through-hole 1204 f for grounding the first and secondground sections 1240 a and 1240 b to a ground section on the bottom sideof the attenuator. Similarly, third ground section 1240 c includes firstthrough-hole 1204 a and fourth ground section 1240 d includes a fourththrough-hole 1204 d for grounding the third and fourth ground sections1240 c and 1240 d to a ground section on the bottom side of theattenuator.

In some examples, the ground section on the bottom side of theattenuator (e.g., in a first portion of the attenuator) electricallycouples first ground section 1240 a, the second ground section 1240 b,the third ground section 1240 c, and the fourth ground section 1240 d,for example, via through-holes 1204 a, 1204 c, 1204 d, and 1204 f.

The attenuator of FIG. 12 includes a first resistive section 1230between the input section 1224 and the third ground section 1240 c, asecond resistive section 1232 between the input section 1224 and thefirst ground section 1240 a, and a third resistive section 1234 betweenthe input section 1224 and the output section 1226. The attenuatorfurther includes a fourth resistive section 1236 between the outputsection 1226 and the fourth ground section 1240 d and a fifth resistivesection 1238 between the output section 1226 and the second groundsection 1240 b. The first 1230, second 1232, third 1234, fourth 1236,and fifth 1238 resistive sections form a “dual pi” attenuator betweenthe input section 1224 and the output section 1226, and similarlybetween through-holes 1204 b and 1204 e.

FIG. 12 includes a schematic trace of a circuit diagram showing the“dual pi” attenuator configuration. As shown, the schematic circuitincludes resistors R₇ (corresponding to first resistive section 1230),R₈ (corresponding to second resistive section 1232), R₉ (correspondingto third resistive section 1234), R₁₀ (corresponding to fourth resistivesection 1236), and R₁₁ (corresponding to fifth resistive section 1238).It will be appreciated that, in such a “dual pi” configurationattenuator, adjusting the values of resistors R₇, R₈, R₉, R₁₀, or R₁₁will adjust the attenuation characteristics of the attenuator. Thus,adjusting the geometry of resistive sections 1230, 1232, 1234, 1236,and/or 1238 can similarly impact the attenuation characteristics of theattenuator, for example, by one or more extensions and/or cutawaysections as described with respect to FIGS. 10 and 11. For example,similar to as discussed with respect to the exemplary “tee” attenuatorin FIG. 10, adjusting various dimensional characteristics of one or moresections, such as the input section 1224, output section 1226, firstground section 1240 a, second ground section 1240 b, third groundsection 1240 c, or fourth ground section 1240 d can customize theresistance of the resistive sections 1230, 1232, 1234, 1236, and/or 1238of the attenuator, and thus the attenuating characteristics of theattenuator.

In the illustrative examples of FIGS. 10-12, the attenuators aregenerally shows as being substantially symmetrical. For instance, invarious embodiments and as described elsewhere herein, sections of theattenuator (e.g., resistive sections) can comprise the same layer(s) ofthe same material(s) at approximately the same thickness(es). In someexamples, resistive sections (e.g., 1030, 1032, 1034 in FIG. 10) eachcomprise approximately the same thickness of a resistive material, suchas shown in resistive layer 372 in FIG. 4A. In some such examples,different resistance values for different resistive sections can beachieved by adjusting the dimensions of the resistive sections. In suchconfigurations, attenuators that are approximately structurallysymmetric in the direction of signal propagation will likely also besymmetric with respect to attenuation of signals. Accordingly, in someembodiments, attenuator chips can be manufactured to be approximatelysymmetric such that the attenuator will attenuate signals approximatelyequally in either direction of signal propagation through chip. Forinstance, in an exemplary embodiment, with respect to FIG. 12,resistance values R₇=R₁₀ and R₈=R₁₁ to promote symmetry in theattenuator. Similarly, with respect to FIG. 11, in some embodiments,resistance values R₄=R₆ to promote attenuator symmetry, and with respectto FIG. 10, in some embodiments, R₁=R₂ to promote attenuator symmetry.

Various examples have been described. The figures and descriptionsherein are exemplary in nature and do not limit the scope of theinvention in any way. Moreover, the drawings of various embodiments areintended to show features and views of various embodiments describedherein, and are not necessarily drawn to scale unless explicitly stated.Such examples are provided to demonstrate various possibleconfigurations and implementations within the scope of the followingclaim(s).

1-20. (canceled)
 21. A passive, high frequency attenuator comprising: asubstrate comprising a substrate material having a first side and asecond side, the second side being opposite the first; a first portioncoupled to the first side of the substrate, the first portioncomprising: an input contact section; an output contact section; and aground section; a second portion coupled to the second side of thesubstrate, the second portion comprising: a first ground sectionpositioned along a first edge of the second side of the substrate; asecond ground section positioned along a second edge of the second sideof the substrate, the second edge being opposite the first edge; and anattenuation section positioned between the first and second groundsections, the attenuation section comprising: an input section; anoutput section; and a plurality of resistive sections positioned betweenthe input section, the output section, and the first ground section; anda plurality of through-holes extending through the substrate andproviding electrical communication between the first side of thesubstrate and the second side of the substrate; and wherein the inputcontact section of the first portion is in electrical communication withthe input section of the attenuation section of the second portion; theoutput contact section of the first portion is in electricalcommunication with the output section of the attenuation section of thesecond portion; and the ground section of the first portion is inelectrical communication with the first ground section of the secondportion and the second ground section of the second portion.
 22. Theattenuator of claim 21, wherein the attenuation section comprises: afirst resistive section providing communication between the inputsection and the first ground section; a second resistive sectionproviding communication between the input section and the outputsection; and a third resistive section providing communication betweenthe output section and the first ground section.
 23. The attenuator ofclaim 22, wherein the attenuation section further comprises: a fourthresistive section providing communication between the input section andthe second ground section; and a fifth resistive section providingcommunication between the output section and the second ground section.24. The attenuator of claim 21, wherein there are no resistive sectionsproviding communication between the input section and the second groundsection or between the output section and the second ground section. 25.The attenuator of claim 24, wherein the attenuation section comprises:an intermediate section; a first resistive section providingcommunication between the input section and the intermediate section; asecond resistive section providing communication between theintermediate section and the first ground section; and a third resistivesection providing communication between the intermediate section and theoutput section.
 26. The attenuator of claim 21, wherein the plurality ofthrough-holes comprises: a first through-hole providing electricalcommunication between the input contact section of the first portion andthe input section of the second portion; a second through-hole providingelectrical communication between the output contact section of the firstportion and the output section of the second portion; a thirdthrough-hole providing electrical communication between the groundsection of the first portion and the first ground section of the secondportion; and a fourth through-hole providing electrical communicationbetween the ground section of the first portion and the second groundsection of the second portion.
 27. The attenuator of claim 26, whereinthe ground section on the first portion comprises a cut or gap dividingthe ground section into separate ground sections; the third through-holeprovides electrical communication between a first of the separate groundsections of the first portion and the first ground section of the secondportion; and the plurality of through-holes further comprises a fifththrough-hole providing electrical communication between a second of theseparate ground sections of the first portion and the first groundsection of the second portion.
 28. The attenuator of claim 26, whereinthe ground section on the first portion comprises a cut or gap dividingthe ground section into separate ground sections; the fourththrough-hole provides electrical communication between a first of theseparate ground sections of the first portion and the second groundsection of the second portion; and the plurality of through-holesfurther comprises a fifth through-hole providing electricalcommunication between a second of the separate ground sections of thefirst portion and the second ground section of the second portion. 29.The attenuator of claim 21, wherein each of the first ground section,the input section, and the output section of the attenuation section ofthe second portion includes a first stack of materials and the pluralityof resistive sections of the attenuation section of the second portioninclude a second stack of materials.
 30. The attenuator of claim 29,wherein the first stack of materials comprises: a thin-film resistivelayer coupled to the second side of the substrate, a thin-film barrierlayer coupled to the thin-film resistive layer, a thin-film conductivelayer coupled to the thin-film resistive layer, and a plating layercoupled to the thin-film conductive layer; and the second stack ofmaterials comprises the thin-film resistive layer and does not includethe thin-film barrier layer, the thin-film conductive layer, or theplating layer.
 31. The attenuator of claim 30, wherein the second stackof materials is a subset of the first stack of materials.
 32. Theattenuator of claim 21, wherein each of the plurality of through-holesis internal to a perimeter of the attenuator such that the perimeter ofthe attenuator does not intersect any of the plurality of through-holes.33. A passive, high frequency attenuator comprising: a substratecomprising a substrate material having a first side and a second side,the second side being opposite the first; a first portion coupled to thefirst side of the substrate and comprising a ground section; a secondportion coupled to the second side of the substrate, the second portioncomprising: a first ground section positioned along a first edge of thesecond side of the substrate; a second ground section positioned along asecond edge of the second side of the substrate; and an attenuationsection positioned between the first and second ground sections, theattenuation section comprising an input section; an output section; anda plurality of resistive sections providing electrical communicationbetween the input section, the output section, and the first groundsection; a first through-hole extending through the substrate andproviding electrical communication between the ground section on thefirst side of the substrate and the first ground section on the secondside of the substrate; and a second through-hole extending through thesubstrate and providing electrical communication between the groundsection on the first side of the substrate and the second ground sectionon the second side of the substrate; such that the first ground sectionand the second ground section on the second side of the substrate areelectrically coupled to one another via the first through-hole, thesecond through-hole, and the ground section on the first side of thesubstrate.
 34. The attenuator of claim 33, wherein the first portioncoupled to the first side of the substrate comprises an input contactsection and an output contact section.
 35. The attenuator of claim 34,further comprising: a third through-hole extending through the substrateand providing electrical communication between the input contact sectionof the first portion and the input section of the attenuation section;and a fourth through-hole extending through the substrate and providingelectrical communication between the output contact section of the firstportion and the output section of the attenuation section.
 36. Theattenuator of claim 33, wherein the plurality of resistive sectionscomprises: a first resistive section between the input section and thefirst ground section; a second resistive section between the inputsection and the output section; and a third resistive section betweenthe output section and the first ground section.
 37. The attenuator ofclaim 36, wherein the plurality of resistive sections further comprises:a fourth resistive section between the input section and the secondground section; and a fifth resistive section between the output sectionand the second ground section.
 38. A passive, high frequency attenuatorcomprising: a substrate comprising a substrate material having a firstside and a second side, the second side being opposite the first; afirst portion coupled to the first side of the substrate, the firstportion comprising: an input contact section; an output contact section;and a ground section; a second portion coupled to the second side of thesubstrate, the second portion comprising: a first ground sectionpositioned along a first edge of the second side of the substrate; asecond ground section positioned along a second edge of the second sideof the substrate, the second edge being opposite the first edge; and anattenuation section positioned between the first and second groundsections, the attenuation section comprising: an input section; anoutput section; and a plurality of resistive sections positioned betweenthe input section, the output section, and the first ground section; anda first through-hole extending through the substrate and providingelectrical communication between the input contact section of the firstportion and the input section of the attenuation section; and a secondthrough-hole extending through the substrate and providing electricalcommunication between the output contact section of the first portionand the output section of the attenuation section; wherein each of thefirst and second through-holes is internal to a perimeter of theattenuator such that the perimeter of the attenuator does not intersecteither the first or the second through-hole.
 39. The attenuator of claim38, further comprising: a third through-hole extending through thesubstrate and providing electrical communication between the firstground section of the second portion and the ground section of the firstportion; and a fourth through-hole extending through the substrate andproviding electrical communication between the second ground section ofthe second portion and the ground section of the second portion.
 40. Theattenuator of claim 39, wherein: the ground section on the first portioncomprises a cut or gap dividing the ground section into separate groundsections comprising a first of the separate ground sections and a secondof the separate ground sections, the third through-hole provideselectrical communication between the first ground section of the secondportion and the first of the separate ground sections of the firstportion; and the attenuator further comprises a fifth through-holeextending through the substrate and providing electrical communicationbetween the first ground section of the second portion and the second ofthe separate ground sections of the first portion.